The present invention relates to an electromagnetic coupling of the type having a pole piece drum and an eddy current drum which cooperate with a coil. The coupling may advantageously be utilized to drive an oil well pump assembly.
The environment around oil well pump assemblies is typically a caustic environment in which hydrogen sulfide combines with water to form acid, which through electrolytic action, will eventually destroy brushes and slip rings in electrical apparatus. The slip rings may actually become so pitted by the electrolytic action that even if the brushes are replaced, the slip rings will continue to act as an abrasive and cause excessive brush wear. If possible, brushes and/or slip rings should be eliminated from apparatus used in the environment around oil well pump assemblies in order to increase the reliability of the apparatus.
In order to provide adequate control of the operation of an oil well pump assembly, it is contemplated that it may be desirable to retrofit an electromagnetic coupling to a motor which was originally provided to drive the oil well pump assembly. The electromagnetic coupling should be readily mounted in association with the existing oil well pump assembly drive motor and be capable of operating for long periods of time, in a relatively caustic environment, with little or no maintenance. Of course, an electromagnetic coupling having these attributes will be useful in conjunction with many different types of apparatus other than oil well pump assemblies.